中文摘要：

镉（Cd）是我国农田土壤首要污染物，在南方一些地区稻米Cd超标严重，土壤Cd风险评估十分必要。采用长沙某地稻田土壤-糙米Cd点对点数据，通过生物富集系数（BCF）和Burr-Ⅲ物种敏感性分布（SSD）方程，构建了基于稻米食品卫生标准（GB2762—2012）和保护95％稻米品种的土壤Cd限值（HC5），探讨了HC5与土壤性质参数的量化关系和预测模型，并与我国土壤环境质量标准（GB15618—1995／2008）进行了比较。结果表明，pH、有机质（OM）和土壤全镉（TCd）对HE5影响显著，分别可控制HC，变异的62．2％、19．4％和18.3％。基于土壤pH和OM（TCd）的两因子模型能对HE，较为准确地预测，决定系数月。可达0．817（0．802）。土壤pH、TCd与HC5呈正相关，而OM与之呈负相关。随着数值的增大，TEd和OM对HC，的影响降低，而pH影响相对稳定。本研究可为科学合理地进行稻田土壤风险管控及产地土壤环境质量基准研究提供一定依据。

英文摘要：

[ Objective ] in South China, where the ric essential to perform soil Cd ris Cadmium （ Cd e produced in k assessment a ） is the major pollutant in farmland soils of China, especially certain areas is very high in over limit rate. It is, therefore, nd explore for major pathways of the food chain getting exposed to Cd pollution. Based on the point-to-point data of Cd in the soil and brown rice of a certain tract of paddy field in Changsha, the Food Health Standard for Rice （ GB 2762-2012 ） and the research target of protecting 95% of the bio-species in the ecosystem, a threshold value for soil Cd was worked out using the biological concentration factor （ BCF ） and SSD （ species sensitivity distribution ） equations, quantitative relationships of HC5 （ hazardous concentrations ） with soil properties and their prediction models discussed and studies done to compare the threshold value with the criteria for Cd in the Standard for Soil Environment Quality of China. [Method] Some foreign research institutions and scholars usually use BCF as an important parameter in assessing effect and variety of the pollutant, and HC5 as the concentration of a substance in soil being toxic to 5% of bio-species in the ecosystem, in other words, protecting 95% of the bio-species in the ecosystem. HCs is the scientific basis for setting up soil environmental quality standards. In the present study, HC5 for Cd in soil was derived using the species sensitivity distribution method and the concept of BCF based on point- to-point field data from paddy soils. Prediction models for Cd crop safety thresholds based on soil properties were also developed and a function of soil physicochemical properties established. [Result] Results show that soil pH is the main soil factor affecting soil Cd food safety thresholds, and followed by organic matter （OM） content and total Cd （TCd） , explaining 62.2%, 19.4% and 18.3% of the variation of HC5 in paddy soil, respectively. The two-factor （ soil pH and OM ） prediction models